Mix the butter, the cream and the sugar in a saucepan and bring to the boil.
Remove the pan from the heat and add the brands and both types of chocolate.
Mix until it melts.
Refrigerate for 3 or 4 hours until the mixture becomes a firm paste.
Make small balls using roughly a tablespoon of the mixture.
Roll them in cocoa powder, icing sugar or granulated sugar.
Refrigerate them or put them in the freezer in an airtight container. (Recipe makes approx. 40 truffles)